Connectors for rods and other connecting elements along the spinal column can be secured to the bony portions of the spinal column to maintain a desired position or orientation of the connecting element relative to the bony portion in a fixed or dynamic relationship. Anchors such as bone screws can be used to secure the connecting elements to the spinal column. However, over time the anchors may move or backout from their inserted position as a result of forces applied to the anchor due to motion of the bony portions. The anchor movement may cause the anchor to impinge on tissue adjacent its implantation location and less effectively maintain the position of the connecting element relative to the spinal column. Accordingly, systems and methods which reduce or prevent the anchor loosening or backing out from its implanted position would be desirable.